Cooling molds for casting metal



Nov. 24, 1964 c. B. PORTER COOLING Moms FOR CASTING METAL Filed May 23,1963 2 Sheets-Sheet 1 .a l0, mm w l Il* l m Dm VO N lili M um WP. Wm LIIl|..| lill l0.. W M nh 0 C U M (.Jn M M l\ O I i- 7 0, 7 -..4: M Illl----\l\- f @kw.: 4 J 1TL i1! 1- |....I..

Nov. 24, 1964 c. B. PORTER 3,157,921

FiledMay 23, 1963 2 Sheets-Sheet 2 l 4. :jf-

/ //,.1\\\\\\\ yy/M United States Patent O 3,157,921 CGING MLDS FRCASTDIG METAL Carroll B. Porter, Metuchen, Nal., assigner to AmericanSmelting and Reining Company, New York, NE., a corporation ol New.lersey Filed May 23, 1963, Ser.. No. 282,734 Claims. (Cl. 22-57.2)

The invention relates to molds for casting metal, and more particularlyto an improved tube construction for cooling the mold.

The invention constitutes an improvement over the tube arrangementdisclosed and claimed in' Patent 2,946,160 granted in the name ofRichard Baier, lohn Stuart Smart, lr., and Albert l. Phillips, znthoughnot limited to the particular mold shown in the patent.

The Baier et al. patent discloses a calie mold for continuous casting.The mold comprises a graphite blocl; having a series of oversize ribbedcooling tubes fitted in drilled passages arranged around the oblong moldpocket. ln general, this mold has performed most satisfactorily, butafter prolonged use under high operating temperatures, the heattransferring ability or" the cooling tubes becomes impaired. rlhe coppertubes become oxidized, particularly on the hot sides facing the moldcavity. The tubes also lose some of their natural temper; they relaxtheir tight solid-to-solid film-free ht with the graphite block. rl`hesechanges cause loss of heat conductivity across the interfa from graphiteblock to co-oling tube. This condition is aggravated by any misuse ofthe mold such as preheating the mold without turning on the coolingwater prior to starting up .a casting operation.

Objects of the present invention are to overcome the above difficultiesand to provide a generally superior tube construction, one that willmaintain tight, solid-to-solid, film-free t between the tubes and thegraphite block for long periods of time, and one in which the Contactpressure between tubes and block may be manually adjusted from time totime.

According to a preferred form of the invention, the holes around themold pocket of the graphite block are provided with offset grooves.Disposed in the holes are silver tubes and disposed in the grooves arebacker strips. The block has a series of transverse holes along thelength of the tubes behind the hacker strips, in which are disposedscrew-threaded adjustable studs. Helical springs are disposed betweenthe studs and the blacker strips so that pressure may be placed againstthe cold sides of the tubes to press their hot sides against the sidesof the holes adjacent the mold pocket.

Other objects and features of the invention will be more apparent fromthe following descrip-tion when considered with the accompanyingdrawings in which:

FIG. 1 is a fragmentary plan view of the end of a cake mold to which theinvention lis applied;

HG. 2 is a fragmentary elevation of the mold of FiG. l, with supportingstructure for the graphite block omitted;

FIG. 3 is a vertical section, taken on the line 3-3 of FIG. l,illustrating the new tube assembly in position in the mold;

FIG. 4 is a transverse section through the tube assembly andadjacentportions of the mold, taken on the line 4-4 of FIG. 2;

FGS. 5 ,and 6 are sections, corresponding to FIG. 4, but showing otherpositions the outer tube may assume relative to its hole under differentoperating conditions, and with tubes of different original sizes.

In the following description and in the claims, various details will beidentified by specific names, for convenience, but they are intended tobe as generic in their application as the art will permit.

3,l57,92l Patented Nov. 24, 19,64

rrlce Like reference characters denote like parts in the several iguresof the drawings.

ln the accompanying drawings and description forming part of thisspecilication, certain specic disclosure of the invention is made forpurposes oi explanation, but it will be undertsood that the details maybe modied :in various respects without departure from the broad aspectof the invention.

Referring now to the drawings, and more panticularly to FIGS. l-4, themold comprises two half-sections of massive graphite blocks 51, 51,clamped together and supported in a box-like metal structure having sideplates 52 and bottom support 61B. The abutting surfaces 61 of the twoblocks are machined to form a tight seal to prevent escape yof moltenmetal from the mold pocket 97.

The interior mold surface 96 forming the walls of the mold pocket 97 aremachined to provide generally llat planar vertical surfaces. Arrangedaround the mold poele et are tube assemblies comprising outer tubescontaining inner tubes 80. The outer tubes are closed by copper caps S3silver-soldered thereto, and the entire mold is covered by top plates 4(omitted in FIGS. 1 and 2).

Except for the construction and mounting of the cooling tubes, the moldof the present invention may be construoted and used in the same way asthe mold described and claimed in the Baier et al. patent. Molten metalis poured intothe top of the mold pocket against the pocket walls 96,and the congealed oblong cake is removed from the bottom of thev mold.As in the patent, cooling water is supplied to the bottoms of the innertubes 3@ in which it tlows upwardly and thence downwardly between theinner tubes and outer tubes 85, as indicated by the arrows shown in FIG.3. The water then falls into collecting tank (not shown).

The graphite block 51 has a series of drilled :and roamed holes lll.Otfset from the holes ttl on the cold side remote from the pocket wall96 tare oitset rectangular grooves 11 extending the length of the holes1b.

Disposed in the holes l@ are a series of circular outer tubes 5 whichpreferably fit rather snugly in the holes when cold. However, thetightness of lit when cold is not too important for reasons discussedbelow. The inner tubes 8d are oval shaped and have a pair of top spacers12 and a pair of bottom spacers 13 welded thereto. lt is suficient thatthe inner tubes 8th and spacers 12, 13 lit loosely in the outer tubes85.

Disposed in the offset grooves 11 are backer strips 14 extending thelength of the tubes 85 and resting on ledge 60 forming part of thebox-like structure supporting the mold. Backer strips 14 have curvedsaddles 1S closely tilting the outer tubes S5. The hacker strips 14 tloosely in their grooves 11, so as to be freely movable under the urgingof the backing springs 16. In this way the outer tubes 85 areelastically held in close contact with the hot sides ofthe bored holes10 adjacent the mold pocket 96.

For maintaining pressure on the backer strips 14, a series of helicalsprings 16 and adjustable studs 17 are provided. In the form shown eachtub-e 85 has four adjusting studs 17 and four springs 16. Each springassembly uses a hole drilled through the graphite block 51, and alsothrough plate 52 where necessary. Each hole comprises an inner bore 13oi reduced diameter housing spring 16, and an outer threaded bore 19 oflarger diameter receiving threaded stud 17. Stud 17 has a socket for anAllen-head wrench and a reduced pin 20 fitting inside the spring 16. Thepressure of outer tubes 85 against the hot side of the tube holes lil isadjusted by turning the threaded studs 17.

The outer tubes 85 are preferably silver. They may be commercial silver99.9% line, or sterling silver 92.5% silver, balance copper.' The studs17, springs 15, and

3 backer strips 14 may be stainless steel. The inner tubes S and spacers12, 13 may be copper.

In general, the above parts may be made of any metals having thenecessary mechanical characteristics, and which will not harmfullycorrode under operating conditions. Silver is preferred for the outertubes because of its ability to resist harmful corrosion at the hot facewhere heat conductivity across the interface between tube and graphiteis most important.

The size of the several parts is not especially critical so long as theyperform their functions of providing elastic pressure and excellent heattransfer at the hot sides of the outer tubes. In a mold for casting acopper cake having a nominal cross section of about 41/2 or 5 inches by25 inches, such as shown in the above Baier et al. patent, the outertubes S5 may be about 20 inches long. The circular outer tube 85 mayhave an outside diameter of 1.000 inch and an inside diameter of 0.960inch, providing a wall thickness of 0.020 inch.

The inner tubes Sti and spacing strips 12, 13 are sutilciently looseinside the outer tubes 85 that they play no part in enabling the outertubes 85 to resist deforming pressure due to springs 16 or due toexpansion of the outer tubes.

The outer tubes 85 have excellent elasticity, that is, ability to returnto original shape when distorted and after the distorting pressure isremoved The elasticity is maintained throughout the range of distortingstrain or movement to which the tube is subjected. Expansion due tooperating temperatures does not subject the tube to stresses above itselastic limit. This temper is maintained for prolonged periods of timeand in spite of overheating.

Referring now to FIGS. 4-6, the tit of the outer tube 85 in the hole ofthe graphite block when cold and under operating conditions may besomewhat as illustrated in these figures, depending upon the originaltit of the tube in the hole. These figures are based partly ontheoretical considerations, and hence this explanation should not beinterpreted in any limiting sense. Regardless of theory, the tube hasperformed most satisfactorily in actual practice. These figures serve toillustrate the ability of the outer tubes to maintain excellent heattransfer contact with the hole wall under operating conditions,regardless of original size of tube.

For example, if the outer tube fits snugly in its hole, or is onlyslightly undersize when cold, it may take a position somewhat asillustrated in FIG. 4 when cold, and when subjected to pressure ofsprings 16. As shown in FIG. 4, the cold side of the tube is spacedslightly from the cold side of the hole. As the tube expands with risein temperature under operating conditions, it increases its area ofcontact with its hole, expanding to a position somewhat as illustratedin FIG. 5. The expansion of the tube also increases pressure of contactwith the hole wall.

As a further example, if the tube is sufiiciently oversize when cold, itmay occupy a position somewhat as illustrated in FIG. 5 when cold andsubjected to the pressure of springs 16. As shown in FIG. 5, the tubecontacts its hole on all sides. Upon rise in temperature under operatingconditions, the tube may bulge or expand into groove 11, occupying aposition somewhat as illustrated in FIG. 6. The expansion of the tubealso increases pressure of contact with the hole wall.

In all cases, regardless of original tit, the Walls of the outer tubesare elastic and have sufiicient temper to exert pressure against thesmooth surfaces of the holes to promote heat transfer therebetween. Thetubes expand more than the graphite with temperature rise. The tubesmain tain heat transfer Contact with the block. The baclrer and extrasprings permit the walls of the tubes to move relative to the smoothsurfaces of the holes and thus relieve fracturing pressure on thegraphite block due to thermal expansion of the tubes.

In any event, the adjustable studs 17 provide a positive means, alwaysunder the control of the operator, to adjust pressure on the outer tubes85 to maintain thc proper fluid-free, solid-to-solid contact between thctubes and the hole walls.

Should the outer tubes lose part of their temper and take on a new set,due to overheating or for some other cause, the studs 17 may be screwedinwardly to further compress the springs 16 to press the hot sides ofthe tubes against the hot sides of the hole wall.

A further advantage of the invention is the greater leeway permitted inthe original tit between outer tube and hole wall, permitting the tubesto fit comparatively loosely when installed in the graphite block, ifdesired. The silver tube has the advantage over a copper tube in that itis free from harmful corrosion at the hot face where it is mostimportant to maintain heat llow. The circular tube shape and continuoussupport by mold wall and baci-:ing strip help prevent collapse of the`tubes under the pressure exerted by springs.

While certain novel features of the invention have been disclosedherein, and are pointed out in the annexed claims, it will be understoodthat, in accordance with the doctrine of equivalents, various omissions,substitutions and changes may be made by those skilled in the artwithout departing from the spirit of the invention.

I claim:

l. In a mold for casting metal, a graphite block having a mold pocket toreceive molten metal, said block having walls with internal passagesarranged around said mold pocket, said passages comprising holes ofround cross section with offset longitudinal grooves, said grooves beinglocated on the opposite sides of said holes from the mold pocket, tubesin said holes, backing strips in said grooves, means for yieldablyurging said backing strips against said tubes and toward the moldpocket.

2. In the mold of claim 1, said backing strips having curved surfacesengaging the curved surfaces of said tubes.

3. In the mold of claim 1, said walls having a series of transverse boreholes, studs threaded in said transverse holes, and springs between saidstuds and backing strips.

4. In the mold of claim 1, inner tubes of oval cross section disposedwithin said first mentioned tubes, spacers at the shorter axes of saidoval cross section, said pacers engaging the outer tubes at pointsadjacent the mold pocket and opposite therefrom.

5. In a mold for continuously casting metal, said mold comprising a bodyincluding a graphite block, said block having a mold pocket open at oneend to receive molten metal and open at the other end to discharge thecongealed casting, said block having internal passages arranged aroundsaid mold pocket, cooling tubes in said passages, backing strips in saidpassages disposed on the sides of said tubes remote from the moldpocket, auxiliary springs disposed between said body and said backingstrips for urging said backing strips against said tubes to press saidtubes against the walls of said passages adjacent the mold pocket.

Baier et al July 26, 1960 Rusterneyer et al, v Jan. 9, 1962

5. IN A MOLD FOR CONTINUOUSLY CASTING METAL, SAID MOLD COMPRISING A BODYINCLUDING A GRAPHITE BLOCK, SAID BLOCK HAVING A MOLD POCKET OPEN AT ONEEND TO RECEIVE MOLTEN METAL AND OPEN AT THE OTHER END TO DISCHARGE THECONGEALED CASTING, SAID BLOCK HAVING INTERNAL PASSAGES ARRANGED AROUNDSAID MOLD POCKET, COOLING TUBES IN SAID PASSAGES, BACKING STRIPS IN SAIDPASSAGES DISPOSED ON THE SIDES OF SAID TUBES REMOTE FROM THE MOLDPOCKET, AUXILIARY SPRINGS DISPOSED BETWEEN SAID BODY AND SAID BACKINGSTRIPS FOR URGING SAID BACKING STRIPS AGAINST SAID TUBES TO PRESS SAIDTUBES AGAINST THE WALLS OF SAID PASSAGES ADJACENT THE MOLD POCKET.